A number of institutional and non-institutional factors hamper electoral coordination and, hence, increase party system fragmentation in the nominal tier of mixed electoral systems. Contrary to expectations, the number of electoral parties is not lower in all old democracies. Nevertheless, the level of democratic experience modifies the effect of other variables like the type of mixed electoral system or the closeness of the races. Econometric tests evaluate this phenomenon in a diverse sample of 15 countries and a total of 57 elections with more than 10,000 observations at the district level.